The user will be confused(why this function just counts for high or normal memory node? does it counts for ZONE_MOVABLE's lru pages?) until someone else tell them N_HIGH_MEMORY is reused to stand for nodes that have any memory.

A.cont) If we introduce N_MEMORY, we can reduce this confusing AND make the code more clearly:

A.example 2) mm/page_cgroup.c use N_HIGH_MEMORY twice:

One is in page_cgroup_init(void): for_each_node_state(nid, N_HIGH_MEMORY) { It means if the node have memory, we will allocate page_cgroup map for the node. We should use N_MEMORY instead here to gaim more clearly.

The second using is in alloc_page_cgroup(): if (node_state(nid, N_HIGH_MEMORY)) addr = vzalloc_node(size, nid); It means if the node has high or normal memory that can be allocated from kernel. We should keep N_HIGH_MEMORY here, and it will be better if the "any memory" semantic of N_HIGH_MEMORY is removed.

B) This reusing is out-dated if we introduce MOVABLE-dedicated node. The MOVABLE-dedicated node should not appear in node_stats[N_HIGH_MEMORY] nor node_stats[N_NORMAL_MEMORY], because MOVABLE-dedicated node has no high or normal memory.

In x86_64, N_HIGH_MEMORY=N_NORMAL_MEMORY, if a MOVABLE-dedicated node is in node_stats[N_HIGH_MEMORY], it is also means it is in node_stats[N_NORMAL_MEMORY], it causes SLUB wrong.